Electrically conductive polymer composite compositions, method for making, and method for electrical conductivity enhancement

Abstract

Inclusion of relatively small amounts of organic ionic species, such as calcium stearate, in the preparation of an electrically conductive polymer composite composition provides a composition having enhanced electrical properties relative to the composite composition lacking the added organic ionic species. As a result of this enhancement, normally insulating materials which rely upon a conductive filler to render them electrically conductive, can be made to achieve a given level of conductivity using less of the conductive filler than would otherwise be required. As a result, the adverse effects of the conductive filler on the polymer's physical properties can be minimized while maintaining a high level of electrical conductivity.

What is claimed is:  
     
       1. An electrically conductive polymer composite composition comprising: 
       (A) an organic polymer matrix;  
       (B) an electrically conductive filler; and  
       (C) a conductivity enhancing agent comprising calcium stearate, said organic polymer matrix (A) comprising polyphenylene ether structural units corresponding to structure I                    
       wherein R 1 -R 4  are independently hydrogen, halogen, C 1 -C 10  alkyl, C 4 -C 20  aryl, or C 4  -C 20  cycloalkyl; and polyamide structural units corresponding to structure II or III                    
       wherein R 5  and R 6  are independently C 1 -C 20  alkylene, C 4 -C 2 0 arylene, or C 5 -C 20  cycloalkylene, R 7  and R 8  are independently hydrogen, C 1 -C 20  alkyl, C 1 -C 20  aryl, C 7 -C 21  aralkyl, or C 5 -C 20  cycloalkyl, R 9  is C 1 -C 20  alkylene, C 4 -C 20  arylene, or C 5 -C 20  cycloalkylene, and R 10  is C 1 -C 20  alkyl, C 6 -C 20 aryl, C 7 -C 21 , aralkyl, or C 5 -C 20 cycloalkyl; 
       said electrically conductive filler (B) comprising carbon fibrils,  
       said component (A) being present in ant amount between about 50 and about 99.9 percent, said component (B) being present in an amount between about 0.1 and about 20 percent and said component (C) being present in an amount between about 0.001 and about 10 percent, based on the total weight of the composition.  
     
     
       2. A composition according to  claim 1  further comprising at least one impact modifying agent, said impact modifying agent being present in an amount between about 0.1 and about 20 weight percent based upon the total weight of the composition. 
     
     
       3. A composition according to  claim 2  in which component (A) comprises poly(2,6-dimethyl-1, 4 -phenylene ether) and nylon 6,6. 
     
     
       4. A method of making an electrically conductive polymer composite composition comprising: 
       (A) an organic polymer matrix;  
       (B) an electrically conductive filler; and  
       (C) a conductivity enhancing agent comprising calcium stearate;  
       said method comprising mixing components (A), (B) and (C) under melt processing conditions,  
       said organic polymer matrix (A) comprising polyphenylene ether structural units corresponding to structure I                    
       wherein R 1 -R 4  are independently hydrogen, halogen, C 1 -C 10  alkyl, C 4 -C 20  aryl, or C 4 -C 20  cycloalkyl; and 
       polyamide structural units corresponding to structure II or III                    
       wherein R 5  and R 6  are independently C 1 -C 20  alkylene, C 4 -C 20  arylene, or C 5 -C 20  cycloalkylene, and R 7  and R 8  are independently hydrogen, C 1 -C 20  alkyl, C6-C 20  aryl, C 7  -C 21 , aralkyl, or C 5 -C 20  cycloalkyl, R 9  is C 1 -C 20  alkylene, C 4 -C 20  arylene, or C 5 -C 20  cycloalkylene, and R 10  is C 1 -C 20  alkyl, C 6 -C 20  aryl, C 7 -C 21  aralkyl, or C 5 -C 20  cycloalkyl; 
       said electrically conductive filler (B) comprising carbon fibrils,  
       said component (A) being present in an amount between about 50 and about 99.9 percent, said component (B) being present in an amount between about 0.1 and about 20 percent and said component (C) being present in an amount between about 0.001 and about 10 percent, based on the total weight of the composition.  
     
     
       5. A method according to  claim 4  further comprising at least one impact modifying agent, said impact modifying agent being present in an amount between about 0.1 and about 20 weight percent based upon the total weight of the composition. 
     
     
       6. A method according to  claim 5  in which component (A) comprises poly(2,6-dimethyl-1,4-phenylene ether) and nylon 6,6. 
     
     
       7. A method of enhancing the electrical conductivity of an electrically conductive polymer composite composition comprising: 
       (A) an organic polymer matrix; and  
       (B) an electrically conductive filler;  
       said method comprising combining components (A) and (B) under melt processing conditions with a conductivity enhancing agent (C) comprising calcium stearate,  
       said organic polymer matrix (A) comprising polyphenylene ether structural units corresponding to structure I                    
       wherein R 1 -R 4  are independently hydrogen, halogen, C 1 -C 10  alkyl, C 4 -C 20  aryl, or C 4 -C 20  cycloalkyl; and 
       polyamide structural units corresponding to structure II or III                    
       wherein R 5  and R 6  are independently C 1 -C 20  alkylene, C 4 -C 20  arylene, or C 5 -C 20  cycloalkylene, R 7  and R 8  are independently hydrogen, C 1 -C 20  alkyl, C 6 -C 20  aryl, C 7 -C 21  aralkyl, or C 5 -C 20  cycloalkyl, R 9  is C 1 -C 20  alkylene, C 4 -C 20  arylene, or C 5 -C 20  cycloalkylene, and R 10  is C 1 -C 20  alkyl, C 6 -C20 aryl, C 7 -C 21 , aralkyl, or C 5 -C 20 cycloalkyl; 
       said electrically conductive filler (B) comprising carbon fibrils,  
       said component (A) being present in an amount between about 50 and about 99.9 percent, said component (B) being present in an amount between about 0.1 and about 20 percent and said component (C) being present in an amount between about 0.001 and about 10 percent, based on the total weight of the composition.  
     
     
       8. A method according to  claim 7  further comprising at least one impact modifying agent, said impact modifying agent being present in an amount between about 0.1 and about 20 weight percent based upon the total weight of the composition. 
     
     
       9. A method according to  claim 8  in which component (A) comprises poly(2,6-dimethyl-1,4-phenylene ether) and nylon 6,6. 
     
     
       10. An electrically conductive polymer composite composition comprising: 
       (A) an organic polymer matrix comprising poly(2,6-dimethyl-1,4-phenylene ether) in an amount equivalent to about 35 to about 65 weight percent, nylon 6,6 in an amount equivalent to about 65 to about 35 weight percent, and an impact modifier in an amount equivalent to about 5 to about 15 weight percent;  
       (B) an electrically conductive filler comprising carbon fibrils in an amount equivalent to from about 0.1 to about 2.0 weight percent; and  
       (C) a conductivity enhancing agent comprising calcium stearate in an amount equivalent to about 0.1 and about 2.0 weight percent; wherein weight percent refers to the weight percent of the component relative to the total weight of the composition.  
     
     
       11. A molded article prepared from the composition of  claim 10 . 
     
     
       12. A method of preparing an electrically conductive polymer composite composition comprising: 
       (A) an organic polymer matrix comprising poly(2,6-dimethyl-1,4-phenylene ether) in an amount equivalent to about 35 to about 65 weight percents nylon 6,6 in an amount equivalent to about 65 to about 35 weight percent, an impact modifier in an amount equivalent to about 5 to about 15 weight percent;  
       (B) an electrically conductive filler comprising carbon fibrils in an amount equivalent to about 0.1 to about 2.0 weight percent; and  
       (C) a conductivity enhancing agent comprising calcium stearate in an amount equivalent to about 0.1 and about 2.0 weight percent;  
       wherein weight percent refers to the weight percent of constituent relative to the total weight of the composition;  
       said method comprising combining components (A), (B) and (C) under melt processing conditions.  
     
     
       13. A method according to  claim 12  wherein the poly(2,6-dimethyl-1,4-phenylene)ether and impact modifier are first melt mixed under melt processing conditions at a temperature in a range between about 270 and 320° C., and thereafter nylon 6,6 carbon fibrils and calcium stearate are added to the mixture of poly(2,6-dimethyl-1,4-phenylene)ether and impact modifier, and the whole is subjected to further melt processing. 
     
     
       14. A method of enhancing the electrical conductivity of an electrically conductive polymer composite composition comprising: 
       (A) an organic polymer matrix comprising poly(2,6-dimethyl-1,4-phenylene ether) in an amount equivalent to about 35 to about 65 weight percent, nylon 6,6 in an amount equivalent to about 6 5 to about 3 5 weight percent, an impact modifier in an amount equivalent to about 5 to about 15 weight percent; and  
       (B) an electrically conductive filler comprising carbon fibrils in an amount equivalent to from about 0.1 to about 2.0 weight percent;  
       wherein weight percent refers to the weight percent of constituent relative to the total weight of the composition;  
       said method comprising combining components (A) and (B) with a conductivity enhancing agent comprising calcium stearate in an amount equivalent to about 0.1 to about 2.0 weight percent calcium stearate based upon the total weight of the composition.